Microwave spectrum of p-chlorostyrene

The microwave spectrum of p-chlorostyrene has been studied in the frequency region 18.0–26.5 GHz. Rotational transitions of the ground state, the first two torsionally excited states and two other vibrational states of the ³⁵Cl isotopic species have been identified. The molecule was found to be planar in the ground state. From intensity measurements, the frequency of the first torsional transition has been estimated to be 35 ± 15 cm^?1.